The capacity and speed of communications systems may be increased by transmitting information in optical form over networks composed of optically transmissive nodes, fibers, waveguides, and the like. High capacity optical communications systems require that many optical signals be frequency division multiplexed in the components of an optical network. An important component for such a system is an optical frequency translator, which may be employed for a variety of signal processing purposes. An optical frequency translator can shift the optical carrier frequency while maintaining the data signal. In a communication system optical frequency translators are used in optical wavelength division multiplex cross-connect switches, for example.
One type of known optical frequency translator is composed of a tunable DBR or Y-branch laser that incorporates a saturable absorber or an optical gain section. However, the performance of these devices have been limited in terms of tuning speed, frequency selectivity, or tuning range. All of these prior devices also have been expensive to implement.